1. Field of the Invention
The present invention relates generally to shearing machines having an upper and lower blades for cutting or shearing sheet-like workpieces such as sheet metals, and more particularly the present invention pertains to adjustments for adjusting the clearance between the upper and lower blades and the inclination of the upper blade to the lower blade depending upon thicknesses of workpieces to be sheared in shearing machines.
2. Description of the Prior Art
As is well-known, shearing machines for cutting or shearing sheet-like workpieces such as sheet metals are provided with an upper movable blade and a lower fixed blade which are flat and elongated in shape and are so arranged as to cooperate with each other to make shearing actions just like a pair of scissors or shears. The lower blade is horizontally fixed with its flat side vertically held, and the upper blade is disposed at an inclination or angle (shear angle) to the lower blade with its flat side vertically held so that it can be vertically moved toward and away from the lower blade to shear workpieces in cooperation therewith. Of course, the upper and lower blades are so disposed that they will overlap each other just like a pair of scissors when the upper blade is lowered to make a shearing action.
In shearing machines of the above described construction, it is necessary to adjust the clearance between the upper and lower blades depending upon thicknesses of workpieces to be sheared in order to perform accurate and fine shearing operations. More particularly, it is desired to make the clearance between the upper and lower blades as small as possible to perform accurate and fine shearing operations, but it is necessary to increase the clearance to shear thicker workpieces so as to decrease the wear of the upper and lower blades. Also, it is likewise necessary to adjust the shear angle namely inclination of the upper blade to the lower blade depending upon the thicknesses of workpieces to be sheared. It is desired to make the inclination of the upper blade as small as possible in order to deformations of workpieces to be sheared, but it is necessary to make the inclination larger to shear thicker workpieces so as to decrease the shearing force required.
Heretofore, it has been customary that the clearance between the upper and lower blades and the shear angle or the inclination of the upper blade are experientially determined and manually adjusted by operators of shearing machines depending upon thicknesses of workpieces to be sheared each time when different thicknesses of workpieces are to be sheared. Therefore, it has been very time-consuming especially where a variety of workpieces different in thickness are to be sheared in small quantities.